Reibi, The 0-Tails

Bestow {1}{b} ( If you cast this card for its
bestow cost, it's an Aura spell with enchant
creature. It becomes a creature again if
it's not attached to a creature.)
Wither ( this deals damage to creatures in the
form of -1/-1 counters.)
Reibi, The 0-Tails and enchanted creature
each get wither and gain +X/+X, where X is the number of creatures in your graveyard.